The present invention relates generally to door latch assemblies that include a door bolt assembly operable by a door handle assembly preferably having a paddle style handle. The handles are selectively positionable in either in up, down, horizontal left or horizontal right configurations. More specifically, the present disclosure relates to a door latch assembly configured to operate with relatively low operating noise.
Examples of existing door latch, door bolt, and door handle assemblies are described in U.S. Pat. Nos. 6,293,598; 7,258,374; 7,481,607; 6,196,599 and 5,730,478, and US Patent Publication No. 2013/0076046A1, all commonly assigned to Architectural Builders Hardware Manufacturing, Inc., and hereby incorporated by reference. Such door latch assemblies include, generally, a door bolt assembly with a latch mechanism, and at least one handle mechanism.
A common problem of conventional door latch and door handle assemblies is that they generate more than desired levels of noise over the ambient noise. In some environments, such levels of noise may be distracting. For example, in hospital work environments, the opening of a patient's room door by a nurse may unnecessarily wake the patient, thereby inhibiting patient rest. In addition, in an operating room environment, a surgeon may be unnecessarily distracted by the opening of a door during a delicate procedure, thereby causing the surgeon to lose focus. Ambient noise in typical hospital work environments is about 40-42 decibels (dB). A conventional door latch and door handle assembly may generate over 30 additional decibels of noise when a door is opened.